1. What is LED Forward Voltage?

The forward voltage (V_f) of an LED is the voltage required for the LED to light up. This voltage varies with temperature, typically decreasing as temperature increases.

2. How Does the Calculator Work?

The calculator uses the forward voltage equation:

Where:

• \( V_f \) — Forward voltage at temperature T (V)
• \( V_{f0} \) — Forward voltage at reference temperature T₀ (V)
• \( k \) — Temperature coefficient (V/°C)
• \( T \) — Current temperature (°C)
• \( T_0 \) — Reference temperature (°C)

Explanation: The equation accounts for the linear relationship between forward voltage and temperature change from the reference point.

3. Importance of Temperature Compensation

Details: Accurate forward voltage calculation is crucial for LED circuit design, especially in environments with temperature variations, to ensure proper current regulation and LED performance.

4. Using the Calculator

Tips: Enter the forward voltage at reference temperature, temperature coefficient, current temperature, and reference temperature (typically 25°C). All values must be valid numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical temperature coefficient for LEDs?
A: Most LEDs have a temperature coefficient between -2mV/°C to -4mV/°C (-0.002 to -0.004 V/°C).

Q2: Why does forward voltage decrease with temperature?
A: As temperature increases, the band gap of the semiconductor material decreases, requiring less voltage to achieve the same current flow.

Q3: Is this relationship linear across all temperatures?
A: The relationship is approximately linear within the LED's normal operating range, but may deviate at extreme temperatures.

Q4: How does this affect LED driver design?
A: Temperature compensation may be needed in precision applications to maintain consistent brightness across temperature variations.

Q5: What's a typical forward voltage for common LEDs?
A: Red LEDs typically have V_f of 1.8-2.2V, white/blue LEDs 3.0-3.6V at room temperature.